[vtkusers] Deriving python classes from vtk classes?

[David Gobbi]

On 23 Jun 2000, Alexandre Guimond wrote:

> Hi there.  I just started playing with python and was hoping that I
> would be able to have python classes inherit from vtk classes.  From
> what I understand, vtk classes are not "classes" in python from which
> I could derive other classes.  Is there a way to simulate such a
> thing, ie deriving vtk classes in python?

The best you can do is write a python class that has the same method names
as the VTK class, and which contains a copy of the VTK class.  If you
do this with e.g. a source or a filter, by simply writing python 
SetInput/GetOutput methods and a few Set/Get methods you can make a
python class that is indistinguishable from a real VTK class.  
You must also ensure that the pipeline behaviour is the same as for
a real VTK class, this can be difficult or impossible sometimes.

There is no way to override virtual methods from a VTK class, or
at least not unless you want to delve into some tricky c++ programming
as well as python programming.

 - David

--
  David Gobbi, MSc                    dgobbi at irus.rri.on.ca
  Advanced Imaging Research Group
  Robarts Research Institute, University of Western Ontario